The present invention relates generally to oil and gas well completion methods, and more particularly, to well completion methods utilizing rubber latex compositions in subterranean formations containing salt zones.
A variety of oil and gas well completion methods have heretofore involved the use of hydraulic cement compositions. Such cement compositions are usually comprised of a water slurry of Portland cement and various additives such as set time accelerators, retarders, fluid loss reducers, dispersants, etc. The cement slurries are pumped into completion or remedial locations within well bores and/or subterranean formations penetrated thereby and allowed to set into hard impermeable masses.
A principal well completion technique which utilizes a cement composition is known as primary well cementing. Primary well cementing involves the placement of a cement composition in the annulus between the walls of the well bore and a conduit, e.g., casing, disposed therein, and allowing the cement composition to set therein whereby the exterior surfaces of the conduit are bonded to the walls of the well bore. The bonding of the conduit within the well bore serves to maintain the conduit in place and to prevent formation fluids from communicating between subterranean formations or zones or to the surface by way of the annulus.
While primary cementing operations utilizing Portland cement compositions have generally been very successful, when such primary cementing is carried out in wells through salt zones wash-out areas in the formation can occur as a result of salt dissolution into non-salt saturated aqueous well bore fluid. Salt zones can also have adverse effects on freshwater cement compositions used in well completion methods, and therefore, salt saturated slurries are often necessary for cementing through these zones. However, the use of a salt saturated cement slurry is often undesired because the salt increases the length of time required for the cement to set. Hence, there are needs for improved well completion methods utilizing compositions which provide protective barriers between the salt zones and fluids being used in such methods.